In my project, I am trying to migrate all usages of
Foo foo = (Foo) beanFactory.getBean(\"name\");
into
Foo foo = beanFactory.
Most Spring apps wire things together on startup, rather than grabbing beans from the context at runtime. Even still, unless you are changing your application context a lot during the regular running of your app, you should not ever fetch a bean more than once.
Given that, if your users are complaining of slowness, it seems your real problem is too many bean lookups; your use of a slower means of doing so has just surfaced the real problem.
I would try moving to Java Config (configure your dependencies in Java, supported in Spring 3.0 I believe) and configuring your app to wire all beans at startup. This also has the advantage that your app just won't start if dependencies can't be met.